Optical alignment system and alignment method thereof

Abstract

The invention discloses an optical alignment system and an alignment method thereof. The optical alignment system comprises a placement structure, a semi-transparent and semi-reflective structure and an optical power meter. The placing structure is used for placing a display device to be aligned, and the semi-transmitting and semi-reflecting structure is located on one side of the placing structure. The semi-transparent and semi-reflective structure is configured to reflect a part of light emitted by the display device to the optical power meter; the placing structure and the semi-transparent and semi-reflective structure are arranged along a first direction, and the optical power meter and the semi-transparent and semi-reflective structure are arranged along a second direction. The placing structure comprises a first position adjusting mechanism and a second position adjusting mechanism which are arranged in the first direction, one of the first position adjusting mechanism and the second position adjusting mechanism is configured to rotate around a datum line relative to the other one, and the datum line passes through the center of the semi-transmitting and semi-reflecting structure and extends in the first direction. According to the optical alignment system, the first position adjusting mechanism and the second position adjusting mechanism which can rotate relatively are arranged to be matched with the semi-transparent and semi-reflective structure and the optical power meter, and the ghosting phenomenon can be relieved.

Description

Technical Field

[0001] Embodiments of the present disclosure relate to an optical alignment system and an alignment method thereof. Background Art

[0002] The virtual reality device includes a display screen and an ultra-short-focus folded optical path (Pancake) located on the light-emitting side of the display screen. By matching the ultra-short-focus folded optical path with the display screen, the required distance between the display screen and the human eye can be greatly reduced, making the virtual reality device lighter and thinner. Summary of the Invention

[0003] Embodiments of the present disclosure provide an optical alignment system and an alignment method thereof.

[0004] An embodiment of the present disclosure provides an optical alignment system including: a placement structure, a semi-transparent and semi-reflective structure, and an optical power meter. The placement structure is used to place a display device to be aligned; the semi-transparent and semi-reflective structure is located on one side of the placement structure. The placement structure and the optical power meter are located on the same side of the semi-transparent and semi-reflective structure, and the semi-transparent and semi-reflective structure is configured to reflect a portion of the light emitted by the display device to the optical power meter; the placement structure and the semi-transparent and semi-reflective structure are arranged along a first direction, and the optical power meter and the semi-transparent and semi-reflective structure are arranged along a second direction, the first direction intersecting the second direction, the placement structure includes a first position adjustment mechanism and a second position adjustment mechanism arranged along the first direction, the first position adjustment mechanism is located between the second position adjustment mechanism and the semi-transparent and semi-reflective structure, and one of the first position adjustment mechanism and the second position adjustment mechanism is configured to rotate relative to the other around a reference line, and the reference line passes through the center of the semi-transparent and semi-reflective structure and extends along the first direction.

[0005] For example, according to an embodiment of the present disclosure, the optical alignment system further includes: a first lens structure located between the optical power meter and the semi-transmissive and semi-reflective structure.

[0006] For example, according to an embodiment of the present disclosure, the optical alignment system further includes: at least one detector, the at least one detector including a first detector, the reference line passing through the first detector, and the transflective structure is further configured to transmit a portion of the light emitted by the display device to the first detector.

[0007] For example, according to an embodiment of the present disclosure, the optical alignment system further includes: a movable component positioned between the at least one detector and the transflective structure; and at least one second lens structure positioned on the movable component. The movable component is configured to adjust the distance between the at least one second lens structure and the corresponding detector.

[0008] For example, according to an embodiment of the present disclosure, the display device to be aligned includes a display screen and an optical structure located on the display side of the display screen, the semi-transparent and semi-reflective structure is located on the side of the optical structure away from the display screen, and at least one of the first position adjustment mechanism and the semi-transparent and semi-reflective structure is configured to move relative to the other in the first direction so that the ratio of the distance between the center of the semi-transparent and semi-reflective structure and the exit pupil plane of the optical structure to the exit pupil distance of the optical structure is not greater than 10%.

[0009] For example, according to an embodiment of the present disclosure, the first position adjustment mechanism and the second position adjustment mechanism are further configured such that one of them moves relative to the other in at least one of the first direction and in a plane perpendicular to the first direction.

[0010] For example, according to an embodiment of the present disclosure, the first position adjustment mechanism and the second position adjustment mechanism are also configured to rotate one of them relative to the other around a first axis parallel to the second direction and around a second axis perpendicular to the first direction and the second direction to adjust the inclination between two components in the display device respectively placed on the first position adjustment mechanism and the second position adjustment mechanism; the first axis, the second axis and the reference line intersect at one point.

[0011] For example, according to an embodiment of the present disclosure, the at least one detector includes multiple detectors, the multiple detectors include multiple second detectors, and the angle between the center lines of two second detectors symmetrically distributed relative to the first detector is 120 degrees.

[0012] For example, according to an embodiment of the present disclosure, one of the first position adjustment mechanism and the second position adjustment mechanism is configured to rotate relative to the other about a reference line at an angle of ±90 degrees.

[0013] For example, according to an embodiment of the present disclosure, the angle between the light-splitting surface of the semi-transmissive and semi-reflective structure and the first direction is 40 to 50 degrees.

[0014] Another embodiment of the present disclosure provides an alignment method applied to the above-mentioned optical alignment system, comprising: placing the display device to be aligned on the placement structure, wherein the display device to be aligned includes a display screen and an optical structure located on the display side of the display screen, the semi-transparent and semi-reflective structure is located on the side of the optical structure away from the display screen, the first position adjustment mechanism is configured to place the optical structure, and the second position adjustment mechanism is configured to place the display screen; rotating one of the first position adjustment mechanism and the second position adjustment mechanism to rotate the display screen and one of the optical structure relative to the other; and detecting the change in optical power of the display device during the above-mentioned rotation process.

[0015] For example, according to an embodiment of the present disclosure, the optical alignment system further includes at least one detector, the at least one detector includes a first detector, the reference line passes through the first detector, the semi-transparent and semi-reflective structure is further configured to transmit a portion of the light emitted by the display device to the first detector, and the alignment method further includes: acquiring an image through the at least one detector to obtain a modulation transfer function.

[0016] For example, according to an embodiment of the present disclosure, the optical alignment system also includes at least one second lens structure, located between the at least one detector and the semi-transparent and semi-reflective structure, and the alignment method also includes: adjusting the distance between the at least one second lens structure and the detector corresponding thereto to detect the position of the virtual image formed by the display device; adjusting at least one of the first parameter, the second parameter and the third parameter according to the position of the virtual image to balance the modulation transfer function and the position of the virtual image, wherein the first parameter includes the distance between the display screen and the optical structure, the second parameter includes the offset distance between the center of the display screen and the center of the optical structure on a plane perpendicular to the first direction, and the third parameter includes the angle between the display surface of the display screen and the optical axis of the lens included in the optical structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions of the embodiments of the present disclosure, the drawings of the embodiments will be briefly introduced below. Obviously, the drawings in the following description only relate to some embodiments of the present disclosure, rather than limiting the present disclosure.

[0018] Figure 1 This is a schematic diagram of a partial cross-sectional structure of a display device.

[0019] Figure 2 for Figure 1 The angle relationship between the transmission axis of the linear polarizer and the slow axis of the quarter-wave plate set on the display screen and the slow axis of the phase delay film and the transmission axis of the reflective polarizer in the optical structure is shown.

[0020] Figure 3 A schematic diagram of a partial planar structure of an optical alignment system provided according to an example of an embodiment of the present disclosure.

[0021] Figure 4 For Figure 3 Schematic diagram of the optical alignment system after placing the display device.

[0022] Figure 5 for Figure 4The diagram shows the relationship between the power ratio received by the optical power meter when the display device is rotating and the relative rotation angle of the first position adjustment mechanism and the second position adjustment mechanism.

[0023] Figure 6 for Figure 5 An enlarged view of local area A in the relationship diagram is shown.

[0024] Figure 7 A partial plan view of an optical alignment system in which a display device is placed is provided according to an example of an embodiment of the present disclosure.

[0025] Figure 8 The present invention provides a flowchart for aligning and fixing the optical structure and display screen in a display device according to an embodiment of the present disclosure. DETAILED DESCRIPTION

[0026] To make the purpose, technical solutions, and advantages of the embodiments of the present disclosure more clear, the technical solutions of the embodiments of the present disclosure will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present disclosure. Obviously, the described embodiments are part of the embodiments of the present disclosure, not all of the embodiments. Based on the described embodiments of the present disclosure, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present disclosure.

[0027] Unless otherwise defined, technical or scientific terms used in this disclosure should have the ordinary meanings understood by people with ordinary skills in the field to which this disclosure belongs. The words "first", "second" and similar terms used in this disclosure do not indicate any order, quantity or importance, but are simply used to distinguish different components. The words "include" or "comprising" and similar terms mean that the elements or objects preceding the word include the elements or objects listed after the word and their equivalents, without excluding other elements or objects.

[0028] Figure 1 FIG. 1 is a schematic diagram of a partial cross-sectional structure of a display device. Figure 1As shown, the display device includes a display screen 011 and an optical structure 02 located on the light-emitting side of the display screen 011. A linear polarizer 012 and a quarter-wave plate 013 are disposed between the display screen 011 and the optical structure 02. For example, the linear polarizer 012 and the quarter-wave plate 013 can be disposed on the display screen 011. The optical film layers in the optical structure 02 can form a folded optical path. The optical structure 02 includes a lens 021, a transflective film 022 located on the lens 021, a phase retarder film 023, a reflective polarizer layer 024, and a linear polarizer layer 025. Image light emitted from the display screen 011 is converted into left-handed or right-handed circularly polarized light after passing through the linear polarizer 012 and the quarter-wave plate 013. For example, the polarization state of right-handed circularly polarized light remains unchanged after passing through the transflective film 022. The right-handed circularly polarized light is incident on the phase retarder film 023 and converted into p-linearly polarized light by the phase retarder film 023. The p-linearly polarized light is then reflected back to the phase retarder film 023 by the reflective polarizer layer 024, where the first reflection occurs. The p-polarized light then passes through the phase retarder film 023 and is converted into right-handed circularly polarized light. This right-handed circularly polarized light reaches the transflective film 022 and is reflected there, where a second reflection occurs. Due to half-wave loss, the reflected light changes from right-handed circularly polarized light to left-handed circularly polarized light. The left-handed circularly polarized light is converted to s-polarized light by the phase retarder film 023. This s-polarized light then passes through the reflective polarizer layer 024 and the linear polarizer film 025 before being emitted to the human eye.

[0029] For example, in Figure 1 When there are multiple lenses in the optical structure shown, different lenses need to be effectively aligned with the center of the optical axis to ensure imaging quality. The alignment method for different lenses can include a canted alignment method; for the phase delay film and reflective polarizing layer included in the optical structure, it is necessary to satisfy that the angle between the slow axis of the phase delay film and the transmittance axis of the reflective polarizing layer is 45 degrees.

[0030] For example, in Figure 1In the display device shown, the optical structure and the display screen can be assembled using a variety of alignment methods to achieve precise alignment between the optical structure and the display screen, thereby facilitating optimal optical performance, such as modulation transfer function (MTF). For example, alignment methods for the optical structure and the display screen can include structurally constrained alignment, such as using a precise gap control device or fixture to control parameters such as the spacing between the optical structure and the display screen, the back focal length of the lens, the offset distance between the center of the display screen and the orthographic projection of the center of the optical structure on a plane perpendicular to the optical axis of the lens, and the tilt angle of the display screen's display surface relative to the lens within an acceptable tolerance range to achieve precise alignment between the display screen and the optical structure. For example, alignment methods for the optical structure and the display screen can include alignment methods that use MTF to evaluate the imaging performance of the optical structure, such as adjusting parameters such as the spacing between the optical structure and the display screen, the back focal length of the lens, the offset distance between the center of the display screen and the orthographic projection of the center of the optical structure on a plane perpendicular to the optical axis of the lens, and the tilt angle of the display screen's display surface relative to the lens based on the characteristics of the MTF curve to achieve optimal MTF.

[0031] Figure 2 for Figure 1 The angle relationship between the transmission axis of the linear polarizer and the slow axis of the quarter wave plate set on the display screen and the slow axis of the phase delay film and the transmission axis of the reflective polarizer in the optical structure is shown. Figure 1 and Figure 2 As shown, the angle between the transmission axis of the linear polarizer 012 on the display screen 011 and the slow axis of the quarter-wave plate 013 is 45°, the angle between the transmission axis of the linear polarizer 012 and the transmission axis of the reflective polarization layer 024 in the optical structure 02 is 90°, and the angle between the slow axis of the quarter-wave plate 013 and the slow axis of the phase delay film 023 in the optical structure 02 is 90°.

[0032] During the research, the inventors of the present application found that: in the process of aligning the optical structure and the display screen, the alignment angle of the optical film in the optical structure and the optical film on the display screen is controlled to maximize the optical efficiency and minimize the ghosting, such as Figure 2 The tolerance of the angular relationship between the transmission axis of the linear polarizer 012 and the transmission axis of the reflective polarizing layer 024, as well as the tolerance of the angular relationship between the slow axis of the quarter-wave plate 013 and the slow axis of the phase delay film 023 are shown. However, it is difficult to control the angles between the above-mentioned optical films.

[0033] Controlling the angle between the optical structure and each optical film in the display screen by means of structurally constrained alignment may result in a loss of optical efficiency, such as causing problems such as ghosting.

[0034] On the one hand, MTF evaluates image resolution using a two-tone black and white diagonal line pattern. It is a key parameter for evaluating the clarity of an optical system. It describes the optical system's ability to transmit details at different spatial frequencies and can provide an image resolution assessment similar to the MTF value. However, it cannot accurately and directly analyze overall optical efficiency losses, such as ghosting. Furthermore, the rotation angle between the optical film in the optical structure and the optical film on the display causes the imaging position of the ghost image of light passing through the folded optical path to be different from the position of the virtual image formed by the light passing through the folded optical path. Therefore, the MTF alignment method cannot evaluate the rotation angle alignment between the optical film in the optical structure and the optical film on the display.

[0035] On the other hand, MTF alignment cannot determine the virtual image distance (VID), such as whether the distance from the virtual image to the human eye has reached the optimal value. If the virtual image distance has not yet reached the optimal value when the MTF value reaches the optimal value, it will cause visual fatigue to the user.

[0036] The present disclosure provides an optical alignment system and an alignment method thereof. The optical alignment system includes a placement structure, a semi-transparent and semi-reflective structure and an optical power meter. The placement structure is used to place a display device to be aligned, and the semi-transparent and semi-reflective structure is located on one side of the placement structure. The placement structure and the optical power meter are located on the same side of the semi-transparent and semi-reflective structure, and the semi-transparent and semi-reflective structure is configured to reflect a portion of the light emitted by the display device to the optical power meter; the placement structure and the semi-transparent and semi-reflective structure are arranged along a first direction, and the optical power meter and the semi-transparent and semi-reflective structure are arranged along a second direction, and the first direction intersects the second direction. The placement structure includes a first position adjustment mechanism and a second position adjustment mechanism arranged along the first direction, the first position adjustment mechanism is located between the second position adjustment mechanism and the semi-transparent and semi-reflective structure, and one of the first position adjustment mechanism and the second position adjustment mechanism is configured to rotate relative to the other around a reference line, and the reference line passes through the center of the semi-transparent and semi-reflective structure and extends along the first direction. The optical alignment system provided by the present disclosure can achieve the alignment of the rotation angles between different optical films in the display device by setting a first position adjustment mechanism and a second position adjustment mechanism that can rotate relatively to match the semi-transparent and semi-reflective structure and the optical power meter, which is beneficial to alleviate the ghosting phenomenon.

[0037] The optical alignment system and alignment method provided by the embodiments of the present disclosure are described below with reference to the accompanying drawings.

[0038] Figure 3 A schematic diagram of a partial planar structure of an optical alignment system provided according to an example of an embodiment of the present disclosure. Figure 4 For Figure 3 Schematic diagram of the optical alignment system after placing the display device.

[0039] like Figure 3 and Figure 4 As shown, the optical alignment system includes a placement structure 100, a semi-transparent and semi-reflective structure 200, and an optical power meter 300. The placement structure 100 is used to place the display device 400 to be aligned, and the semi-transparent and semi-reflective structure 200 is located on one side of the placement structure 100. For example, the semi-transparent and semi-reflective structure 200 is located on the light-emitting side of the display device 400. The placement structure 100 and the optical power meter 300 are located on the same side of the semi-transparent and semi-reflective structure 200, and the semi-transparent and semi-reflective structure 200 is configured to reflect a portion of the light emitted by the display device 400 to the optical power meter 300. For example, the optical power meter 300 is used to measure the energy intensity, such as power, of the optical signal reflected thereon by the semi-transparent and semi-reflective structure 200. For example, the optical power meter 300 can measure the absolute optical power of the light reflected thereon by the semi-transparent and semi-reflective structure 200, and can also be used to calculate optical power loss, such as relative measurement. For example, the optical power meter 300 may be composed of a photodetector and a display unit. The photodetector converts the received optical signal into an electrical signal, which is then processed and displayed as an actual optical power value.

[0040] like Figure 3 and Figure 4 As shown, the placement structure 100 and the transflective structure 200 are arranged along a first direction, and the optical power meter 300 and the transflective structure 200 are arranged along a second direction, with the first direction intersecting the second direction. For example, the first direction may be the X direction, and the second direction may be the Y direction. For example, the angle between the first direction and the second direction may be 80 to 100 degrees, such as 90 degrees. For example, the first direction and the second direction may be interchangeable.

[0041] like Figure 3 and Figure 4 As shown, the placement structure 100 includes a first position adjustment mechanism 110 and a second position adjustment mechanism 120 arranged along a first direction. The first position adjustment mechanism 110 is located between the second position adjustment mechanism 120 and the transflective structure 200. One of the first position adjustment mechanism 110 and the second position adjustment mechanism 120 is configured to rotate relative to the other about a reference line ZL, which passes through the center of the transflective structure 200 and extends along the first direction. For example, the first position adjustment mechanism 110 may be fixed in position and the second position adjustment mechanism 120 may rotate about the reference line ZL, or the second position adjustment mechanism 120 may be fixed in position and the first position adjustment mechanism 110 may rotate about the reference line ZL, or both the first position adjustment mechanism 110 and the second position adjustment mechanism 120 may rotate about the reference line ZL.

[0042] The optical alignment system provided in the present disclosure can achieve the alignment of the rotation angles between different optical films in the display device 400 by setting a first position adjustment mechanism 110 and a second position adjustment mechanism 120 that can rotate relatively to match the semi-transparent and semi-reflective structure 200 and the optical power meter 300, which is beneficial to alleviate the ghosting phenomenon.

[0043] For example, Figure 3 As shown, the first position adjustment mechanism 110 and the second position adjustment mechanism 120 can be a placement platform or a clamping structure.

[0044] For example, Figure 3 As shown, the semi-transparent and semi-reflective structure 200 has the functions of reflection and transmission. For example, the semi-transparent and semi-reflective structure 200 includes a splitting surface, which reflects 40% to 60% of the light incident thereon and transmits 60% to 40%, or the splitting surface reflects 50% of the light incident thereon and transmits 50%. For example, the center of the semi-transparent and semi-reflective structure 200 can be the geometric center of the splitting surface. For example, the semi-transparent and semi-reflective structure 200 can be a beam splitter, such as a beam splitter can include a transparent flat plate and a film layer for transmitting and reflecting light coated on the transparent flat plate; such as a beam splitter can include two prisms glued into a cube and a film layer for transmitting and reflecting light coated on the 45° right-angle prism inclined surface of the prism.

[0045] For example, Figure 4 As shown, the display device 400 to be aligned includes a display screen 410 and an optical structure 420 located on the display side of the display screen 410. The transflective structure 200 is located on a side of the optical structure 420 away from the display screen 410. The first position adjustment mechanism 110 is configured to position the optical structure 420, and the second position adjustment mechanism 120 is configured to position the display screen 410. For example, the display device 400 to be aligned can be a near-eye display device 400, such as a virtual reality display device 400.

[0046] For example, Figure 4 As shown, a first phase retarder film 411 and a first linear polarization layer 412 are provided on the light-emitting surface of the display screen 410. The optical structure 420 includes at least one lens 421, and a transflective film 422, a second phase retarder film 423, and a reflective polarization layer 424 located on the at least one lens 421. The transflective film 422 is closer to the display screen 410 than the second phase retarder film 423 and the reflective polarization layer 424. For example, the optical structure 420 further includes a second linear polarization layer (not shown in the figure) located on the reflective polarization layer 424 away from the transflective film 422. For example, Figure 4The second phase retarder film 423 is schematically shown as being positioned between the transflective film 422 and the reflective polarizing layer 424, but the present invention is not limited thereto. The second phase retarder film 423 may be positioned on a side of the reflective polarizing layer 424 away from the transflective film 422. For example, the transflective film 422 may be positioned between the lens 421 and the display screen 410, and the reflective polarizing layer 424 may be positioned on a side of the lens 421 away from the display screen 410 to achieve light reflection in the lens 421.

[0047] For example, Figure 4 As shown, the first phase retarder film 411 and the second phase retarder film 423 are both quarter-wave plates (QWPs). For example, the angle between the transmission axis of the first linear polarization layer 412 on the display screen 410 and the slow axis of the first phase retarder film 411 is 45°.

[0048] For example, Figure 4 As shown, the reflective polarizing layer 424 functions as follows: the film layer has a transmission axis direction, the transmittance of the polarization component of the incident light parallel to the transmission axis direction (such as one of the s-polarized light and the p-polarized light) is greater than the transmittance of the polarization component perpendicular to the transmission axis direction (such as the other of the s-polarized light and the p-polarized light), and the reflectivity of the polarization component parallel to the transmission axis direction is less than the reflectivity of the polarization component perpendicular to the transmission axis direction. For example, the reflective polarizing layer 424 can also be referred to as a polarization splitting film. For example, the transmittance of polarized light parallel to the transmission axis direction of the reflective polarizing layer 424 is not less than 85%, such as not less than 90%, such as not less than 95%, such as not less than 98%; and the reflectivity of polarized light perpendicular to the transmission axis direction of the reflective polarizing layer 424 is not less than 85%, such as not less than 90%, such as not less than 95%, such as not less than 98%. For example, the angle between the slow axis of the second phase retarder film 423 and the light transmission axis of the reflective polarizing layer 424 is 45°.

[0049] For example, Figure 4 As shown, one of the first position adjustment mechanism 110 and the second position adjustment mechanism 120 is configured to rotate relative to the other around a reference line so that one of the first phase delay film 411 on the display screen 410 and the second phase delay film 423 in the optical structure 420 rotates relative to the other around a reference line so that the slow axis of the first phase delay film 411 and the slow axis of the second phase delay film 423 rotate relative to each other, and the optical power meter 300 is configured to detect the optical power of the direct light emitted by the display device 400 and incident thereon after being reflected by the semi-transparent and semi-reflective structure 200 during the above-mentioned rotation process of the first phase delay film 411 and the second phase delay film 423, so as to detect the degree of ghosting caused by the above-mentioned direct light.

[0050] For example, Figure 4As shown, one of the first position adjustment mechanism 110 and the second position adjustment mechanism 120 is configured to rotate relative to the other around a reference line so that one of the first linear polarization layer on the display screen 410 and the reflective polarization layer 424 in the optical structure 420 rotates relative to the other around the reference line, so that the transmission axis of the first linear polarization layer 412 and the transmission axis of the reflective polarization layer 424 rotate relative to each other, and the optical power meter 300 is configured to detect the optical power of the direct transmitted light emitted from the first linear polarization layer and the reflective polarization layer 424 in the display device 400 during the above rotation process and then incident thereon after being reflected by the semi-transparent and semi-reflective structure 200, so as to detect the degree of ghosting caused by the above direct transmitted light.

[0051] For example, Figure 3 and Figure 4 As shown, the reference line ZL may be a straight line where the optical axis of the lens included in the optical structure 420 is located. For example, the optical axis of the lens included in the optical structure 420 extends along the first direction.

[0052] Figure 5 for Figure 4 The diagram shows the relationship between the power ratio received by the optical power meter 300 when the display device 400 is rotating and the relative rotation angle of the first position adjustment mechanism 110 and the second position adjustment mechanism 120 . Figure 6 for Figure 5 The diagram shows an enlarged view of region A. The power ratios mentioned above refer to the percentage of received optical power to transmitted optical power.

[0053] For example, Figure 5 and Figure 6 As shown, when the optical structure 420 rotates relative to the display screen 410 at an angle of 0 to 360 degrees, the power of the light received by the optical power meter 300 shows an "M"-shaped change trend. When the optical structure 420 rotates relative to the display screen 410 at an angle of 180 to 190 degrees, the power of the light received by the optical power meter 300 accounts for less than 6%. At this time, the power of the direct light in the image displayed by the display device 400 is relatively low, which is conducive to solving the ghosting problem.

[0054] For example, when the optical structure and the display screen are completely aligned, the light emitted from the display screen needs to pass through the return light path to be emitted. In this process, more light is lost (for example, the light that is refracted and reflected in the optical structure is partially lost when passing through the corresponding optical interface, and this lost part of the light should not be emitted from the light-emitting side under normal circumstances). Therefore, when the display screen and the optical structure are aligned, the optical power of the emitted light is the lowest. In the non-aligned position, in addition to the light emitted through the normal return light path, there is also direct light, and there is no light loss in the direct light, so the overall output light power is higher at this time.

[0055] The optical alignment system provided by the present disclosure can achieve the alignment of the rotation angle between the slow axis of the first phase delay film 411 located on the display screen 410 side of the display device 400 and the second phase delay film 423 in the optical structure 420, as well as the alignment of the transmission axis of the first linear polarization layer located on the display screen 410 side and the reflective polarization layer 424 in the optical structure 420, by setting a first position adjustment mechanism 110 and a second position adjustment mechanism 120 that can rotate relative to each other, which is beneficial to alleviate the ghosting phenomenon.

[0056] In some examples, such as Figure 3 and Figure 4 As shown, one of the first position adjustment mechanism 110 and the second position adjustment mechanism 120 is configured to rotate at an angle of ±90 degrees relative to the other about a reference line. For example, one of the first position adjustment mechanism 110 and the second position adjustment mechanism 120 is configured to rotate at an angle of ±60 degrees relative to the other about a reference line. For example, one of the first position adjustment mechanism 110 and the second position adjustment mechanism 120 is configured to rotate at an angle of ±45 degrees relative to the other about a reference line. For example, one of the first position adjustment mechanism 110 and the second position adjustment mechanism 120 is configured to rotate at an angle of ±30 degrees relative to the other about a reference line. For example, one of the first position adjustment mechanism 110 and the second position adjustment mechanism 120 is configured to rotate at an angle of ±15 degrees relative to the other about a reference line. For example, one of the first position adjustment mechanism 110 and the second position adjustment mechanism 120 is configured to rotate at an angle of ±10 degrees relative to the other about a reference line. For example, one of the first position adjustment mechanism 110 and the second position adjustment mechanism 120 is configured to rotate at an angle of ±5 degrees relative to the other about a reference line.

[0057] When the optical structure 420 and the display screen 410 are placed in the preset positions of the first position adjustment mechanism 110 and the second position adjustment mechanism 120 respectively, the optical films located on the two position adjustment mechanisms have a certain angle deviation. By adjusting the two position adjustment mechanisms to rotate relatively to a smaller angle, such as within 180 degrees, the angle with the lowest direct light power can be aligned to facilitate adjustment.

[0058] In some examples, such as Figure 3 and Figure 4 As shown, the optical alignment system further includes a first lens structure 510 located between the optical power meter 300 and the transflective structure 200. For example, the first lens structure 510 is configured to converge the light reflected from the transflective structure 200 to the optical power meter 300. For example, the first lens structure 510 may include at least one lens. For example, the first lens structure 510 may include at least one convex lens.

[0059] For example, Figure 3 and Figure 4 As shown, the optical axis of the first lens structure 510 extends along the second direction. For example, the optical axis of the first lens structure 510 passes through the center of the transflective structure 200. For example, the straight line on which the optical axis of the optical structure 420 lies and the straight line on which the optical axis of the first lens structure 510 lies intersect at the center of the transflective structure 200.

[0060] In some examples, such as Figure 4 As shown, at least one of the first position adjustment mechanism 110 and the semi-transparent and semi-reflective structure 200 is configured to move relative to the other in the first direction so that the ratio of the distance between the center of the semi-transparent and semi-reflective structure 200 and the exit pupil plane EP of the optical structure 420 to the exit pupil distance ER of the optical structure 420 is not greater than 10%. The distance between the center of the semi-transparent and semi-reflective structure 200 and the exit pupil plane EP of the optical structure 420 refers to the distance between the two in the first direction. For example, the position of the semi-transparent and semi-reflective structure 200 is fixed, and the first position adjustment mechanism 110 is adjusted to move relative to the semi-transparent and semi-reflective structure 200 in the first direction to adjust the center of the semi-transparent and semi-reflective structure 200 to be within 10% of the upper and lower deviations of the optimal exit pupil distance (Eye Relief). The "upper and lower deviations" here refer to the distances on both sides of the exit pupil plane in the first direction and the distances between the exit pupil plane and the exit pupil plane are less than 10% of the exit pupil distance ER.

[0061] By adjusting the distance between the semi-transmissive and semi-reflective structure 200 and the optical structure 420 so that the center of the semi-transmissive and semi-reflective structure 200 is within 10% of the optimal exit pupil distance, the optical power meter can detect the power of the direct light at the exit pupil plane.

[0062] In some examples, such as Figure 3 and Figure 4 As shown, the optical alignment system further includes: at least one detector 600, the at least one detector 600 including a first detector 610, the reference line passing through the first detector 610, and the semi-transmissive and semi-reflective structure 200 being further configured to transmit a portion of the light emitted from the display device 400 to the first detector 610. For example, the semi-transmissive and semi-reflective structure 200 reflects a portion of the light emitted from the display device 400 and incident on its spectroscopic surface to the optical power meter 300, and transmits another portion to the detector 600. For example, the number of first detectors 610 is one, such as the first detector 610 can be a detector 600 located in the center area. For example, the at least one detector 600 can include one detector 600, namely, the first detector 610.

[0063] For example, Figure 3 and Figure 4As shown, the ratio of the distance between the center of the first detector 610 and the exit pupil plane EP of the optical structure 420 to the exit pupil distance ER of the optical structure 420 is no greater than 40%. The center of the first detector 610 is located within a 40% deviation above and below the optimal exit pupil distance (Eye Relief). By placing the detector as close as possible to the exit pupil plane, the clarity of the image detected by the detector is maximized, thereby achieving clear imaging.

[0064] In some examples, such as Figure 3 As shown, the angle between the light-splitting surface of the semi-transparent and semi-reflective structure 200 and the first direction is 40 to 50 degrees. By setting the angle between the light-splitting surface of the semi-transparent and semi-reflective structure 200 and the first direction, the relative positions of the placement structure 100, the semi-transparent and semi-reflective structure 200, the optical power meter 300, and the detector 600 can be adjusted. This allows the optical power meter 300 to receive light reflected by the semi-transparent and semi-reflective structure 200 while the detector receives light transmitted by the semi-transparent and semi-reflective structure 200 or light that directly enters the detector without passing through the semi-transparent and semi-reflective structure 200, thereby achieving a compact arrangement of the above-mentioned multiple structures to save space.

[0065] For example, Figure 3 and Figure 4 As shown, the detector can be an image sensor. For example, the image detector can be used to capture and convert optical signals into electrical signals, such as sensing and quantifying changes in light intensity and converting these into digital signals to form an image. For example, the image detector can be a charge-coupled device (CCD) or a complementary metal oxide semiconductor (CMOS) image sensor. For example, image light emitted by the display device 400 is incident on the detector to generate a test image. This test image is used to analyze the MTF and, in turn, evaluate the clarity of the optical structure 420.

[0066] The optical alignment system provided by the present disclosure can greatly alleviate the ghosting phenomenon while evaluating the clarity of the display device 400 by setting a semi-transparent and semi-reflective structure 200 and an optical power meter 300, and setting the relative position relationship of the placement structure 100, the semi-transparent and semi-reflective structure 200, the optical power meter 300 and the detector 600.

[0067] For example, Figure 3 and Figure 4As shown, the detector can be connected to a processor (not shown). After the detector acquires the test image, the processor extracts the edge spread function (ESF), obtains the line spread function (LSF), calculates the MTF, and analyzes the MTF curve. For example, using the slant edge method, the edge spread function (ESF) can be extracted from the test image. For example, the ESF can be obtained by measuring the change in light intensity at the sharp edge in the image; then, by differentiating the ESF, the line spread function (LSF) is obtained. The LSF represents the first-order derivative of the light intensity with respect to position; the LSF is converted to the frequency domain through Fourier transform (FT), and the obtained amplitude spectrum is the MTF. The MTF is usually normalized, and its value is ideally 1 (or 100%), indicating perfect contrast transfer; analyzing the MTF curve can understand the performance of the system at different spatial frequencies. The slower the MTF curve decreases, the better the resolution of the system.

[0068] In some examples, such as Figure 3 and Figure 4 As shown, the first position adjustment mechanism 110 and the second position adjustment mechanism 120 are further configured to move relative to the other along at least one of a first direction and a plane perpendicular to the first direction.

[0069] In some examples, such as Figure 3 and Figure 4 As shown, the first position adjustment mechanism 110 and the second position adjustment mechanism 120 are further configured to rotate relative to the other about a first axis FA parallel to the second direction and about a second axis SA perpendicular to the first and second directions to adjust the inclination between two components of the display device 400 respectively placed on the first position adjustment mechanism 110 and the second position adjustment mechanism 120. The first axis FA, the second axis SA, and the reference line ZL intersect at a point. For example, the point where the first axis FA, the second axis SA, and the reference line ZL intersect can be an origin, such as located at the first position adjustment mechanism 110 or the second position adjustment mechanism 120.

[0070] For example, Figure 4As shown, the distance between the first position adjustment mechanism 110 and the second position adjustment mechanism 120 in a first direction is adjustable to adjust the distance between the display screen 410 and the optical structure 420, i.e., the first parameter. For example, the first position adjustment mechanism 110 can move relative to the second position adjustment mechanism 120 in a plane perpendicular to the first direction to adjust the offset distance between the orthographic projections of the center of the display screen 410 and the center of the optical structure 420 on the plane perpendicular to the first direction, i.e., the second parameter. For example, the first position adjustment mechanism 110 can be deflected relative to the second position adjustment mechanism 120 to adjust the angle between the display surface of the display screen 410 and the optical axis of the lens included in the optical structure 420, or the angle between the normal to the display surface of the display screen 410 and the optical axis of the lens, i.e., the third parameter, which reflects the relative tilt of the display surface of the display screen 410 and the optical structure 420. For example, the above-mentioned "inclination between the two components" refers to the reference that the display surface of the display screen 410 is perpendicular to the optical axis of the optical structure 420. The greater the deviation from the reference, the greater the inclination; or it means that the greater the angle between the normal of the display surface and the optical axis of the lens of the optical structure 420, the greater the inclination.

[0071] By adjusting at least one of the first parameter, the second parameter, and the third parameter, the MTF can be adjusted to an optimal value, so as to achieve clear imaging of the optical structure 420 .

[0072] In some examples, such as Figure 3 As shown, the optical alignment system also includes a movable part 700 and at least one second lens structure 520, the movable part 700 is located between at least one detector 600 and the semi-transparent and semi-reflective structure 200, and the second lens structure 520 is located on the movable part 700; the movable part 700 is configured to adjust the distance between the above-mentioned at least one second lens structure 520 and the corresponding detector 600, such as so that the detector 600 can detect the virtual image distance (VID) of the display device 400, which refers to the distance from the human eye to the virtual image displayed by the display device 400.

[0073] The optical alignment system provided by the present disclosure can monitor the virtual image distance (VID) of the optical structure 420 by setting a movable second lens structure 520 between the detector 600 and the semi-transparent and semi-reflective structure 200, and further adjust at least one of the above-mentioned first parameter, second parameter and third parameter according to the virtual image distance initially monitored to optimize the virtual image distance of the optical structure 420, so as to prevent the user from visual fatigue and improve the user experience of the display device 400. At this time, the optical structure 420 and the display screen 410 achieve the optimal alignment position while minimizing ghosting and balancing MTF and VID.

[0074] For example, Figure 3As shown, the movable component 700 may include a slide extending along the first direction and a placement platform or clamping structure connected to the slide for fixing the second lens structure 520, and drive the second lens structure 520 to move along the first direction relative to the detector 600.

[0075] For example, Figure 3 As shown, the second lens structure 520 may include at least one lens. For example, the second lens structure 520 may include at least one convex lens. For example, the second lens structure 520 may include a lens group.

[0076] For example, Figure 3 As shown, at most one second lens structure 520 is disposed between the same detector 600 and the placement structure 100 , and each second lens structure 520 includes at least one lens.

[0077] For example, Figure 4 As shown, the detector 600, such as a camera, is used to capture the virtual image displayed by the display device 400 to convert the visual distance of the virtual image into the object distance of a real object for measurement. For example, by adjusting the distance between the second lens structure 520 and the detector 600, the overall focus position of the detector 600 can be adjusted so that the relative clarity of the virtual image captured by the detector 600 reaches a critical point. At this point, the virtual image coincides with the perspective position of the detector 600, and the perspective distance of the detector 600 is the VID. The VID detected at this time may not be the optimal VID. By adjusting at least one of the first parameter, the second parameter, and the third parameter, the VID can be optimized to be as close to the optimal VID as possible, thereby balancing the MTF and VID, so that the display screen 410 and the optical structure 420 are aligned to achieve optimal imaging.

[0078] For example, the VID measurement process described above is based on edge-based spatial frequency response measurement (e-SFR), which quantitatively assesses the relative change in image sharpness during the measurement process. The relationship between the focus ring scale points (referenced to the actual object distance) and relative sharpness is plotted. SFR is defined as the relative amplitude response of the imaging system to the input spatial frequency. The remaining MTF definitions are similar, measuring the degree of contrast reduction as a function of spatial frequency.

[0079] Figure 7 A partial plan view of an optical alignment system in which a display device is placed is provided according to an example of an embodiment of the present disclosure. Figure 7 The example shown is the same as Figure 4 The examples shown differ in the number of detectors.

[0080] In some examples, such as Figure 7 As shown, the at least one detector 600 includes multiple detectors 600, and the multiple detectors 600 include multiple second detectors 620. For example, the second detectors 620 can be edge detectors. For example, the angle between the centerlines of two second detectors 620 symmetrically distributed relative to the first detector 610 is 120 degrees. By setting the number of detectors to multiple, it is convenient to measure the virtual image distance of the display device 400 at a wider field of view. For example, the virtual image distance of the display device 400 within a 120-degree field of view can be measured.

[0081] For example, Figure 7 Three detectors are schematically shown, which can represent three columns of detectors. For example, the number of detectors in each column can be three, that is, the optical alignment system can include nine detectors. For example, a second lens structure 520 is provided between at least one detector 600 and the placement structure 100, such as a second lens structure 520 is provided between each detector 600 and the placement structure 100. For example, the optical path of the image light emitted from the display device 400 incident on all detectors 600 passes through the semi-transparent and semi-reflective structure 200, or the optical path of the image light emitted from the display device 400 incident on some detectors passes through the semi-transparent and semi-reflective structure 200, and the optical path of the image light emitted from the display device 400 incident on another part of the detectors does not pass through the semi-transparent and semi-reflective structure 200.

[0082] For example, taking five display devices 400 as an example, with the optimal VID set to 1500 mm, Table 1 below shows the nine MTF values ​​of the five display devices 400 measured by the nine detectors C1-C9 and the VID value measured by the first detector 610 when only the MTF is adjusted to the optimal value. Table 2 below shows the nine MTF values ​​of the five display devices 400 measured by the nine detectors and the VID value measured by the first detector 610 after adjusting at least one of the first, second, and third parameters to balance MTF and VID. As can be seen from Tables 1 and 2, by adjusting at least one of the first, second, and third parameters, the VID value can be adjusted to a value close to the optimal value with minimal impact on the optimal MTF value, thereby meeting the user's requirements for the virtual image formed by the display devices 400.

[0083] Table 1

[0084] quantity VID(mm) C1 C2 C3 C4 C5 C6 C7 C8 C9 1 1486 63.4 48.4 45 48.3 48.6 49.1 54.9 50.3 53.9 2 1409 63.5 49 45.4 49.1 48.1 48.5 54.5 51.4 53.5 3 1395 64 49.1 45.5 48.9 47.9 48.8 54.4 51.1 54.5 4 1356 64.3 48.1 45.5 48.2 49.5 49 55.1 51.5 53.5 5 1479 63.5 48.6 44.8 48.5 48.9 49.2 55.5 51.2 53.6

[0085] Table 2

[0086] quantity VID(mm) C1 C2 C3 C4 C5 C6 C7 C8 C9 1 1506.4 63.4 48.4 45 48.8 48.9 49.3 55.1 50.6 53.9 2 1513.1 63.6 48.8 45 48.7 49.3 49.4 55.5 51.1 54 3 1506.4 63.7 48.4 44.6 48.7 49.3 49.4 55.2 50.9 54 4 1513.1 63.4 48.6 44.5 48.7 49.5 49.5 55.2 50.5 54.2 5 1506.4 63.8 48.5 44.4 48.9 49.5 49.6 55.2 50.9 54.1

[0087] For example, the nine detectors shown in Tables 1 and 2 respectively collect MTF and VID under different field of view angles. For example, the positions of the nine detectors are distributed as follows: the first row includes C2, C7 and C3, the second row includes C6, C1 and C8, and the third row includes C5, C9 and C4, where C1 is the first detector 610, and C2-C9 are all second detectors 620. For example, C6 and C8 are two second detectors 620 symmetrically distributed relative to the first detector 610, and C7 and C9 are two second detectors 620 symmetrically distributed relative to the first detector 610.

[0088] Another embodiment of the present disclosure provides an alignment method applied to the above optical alignment system, referring to Figure 3 、 Figure 4 as well as Figure 7 The alignment method includes: placing a display device 400 to be aligned on a placement structure 100, wherein the display device 400 to be aligned includes a display screen 410 and an optical structure 420 located on the display side of the display screen 410, the semi-transmissive and semi-reflective structure 200 is located on a side of the optical structure 420 away from the display screen 410, the first position adjustment mechanism 110 is configured to place the optical structure 420, and the second position adjustment mechanism 120 is configured to place the display screen 410; rotating one of the first position adjustment mechanism 110 and the second position adjustment mechanism 120 to rotate one of the display screen 410 and the optical structure 420 relative to the other; and detecting a change in optical power of the display device 400 during the above rotation process.

[0089] For example, a cross target is displayed on the display screen 410; one of the display screen 410 and the optical structure 420 is rotated relative to the other in a direction around the optical axis of at least one lens included in the optical structure 420; the optical power meter 300 detects the change in the optical power of the display device 400 during the above rotation process.

[0090] By rotating the first position adjustment mechanism 110 and the second position adjustment mechanism 120 to detect the optical power, the rotation angle between the slow axis of the first phase delay film 411 located on the display screen 410 side of the display device 400 and the second phase delay film 423 in the optical structure 420 can be aligned, as can the transmission axis of the first linear polarization layer located on the display screen 410 side and the reflective polarization layer 424 in the optical structure 420, which is beneficial to alleviate the ghosting phenomenon.

[0091] In some examples, the alignment method further includes: acquiring an image through at least one detector to obtain a modulation transfer function. The method for the detector to obtain the modulation transfer function can refer to the above description.

[0092] For example, the first parameter includes the distance between the display screen 410 and the optical structure 420, the second parameter includes the offset distance between the orthographic projections of the center of the display screen 410 and the center of the optical structure 420 on a plane perpendicular to the first direction, and the third parameter includes the angle between the display surface of the display screen 410 and the optical axis of the lens included in the optical structure 420. By adjusting at least one of the first parameter, the second parameter, and the third parameter to adjust the modulation transfer function to an optimal value, the ghosting phenomenon can be greatly alleviated while evaluating the clarity of the display device 400. For detailed characteristics of the first parameter, the second parameter, and the third parameter, please refer to the above description.

[0093] In some examples, the alignment method further includes: adjusting the distance between at least one second lens structure 520 and its corresponding detector to measure the position of the virtual image formed by the display device 400; adjusting at least one of the first parameter, the second parameter, and the third parameter according to the position of the virtual image to balance the modulation transfer function and the position of the virtual image.

[0094] By further adjusting at least one of the first parameter, the second parameter and the third parameter, the virtual image distance of the optical structure 420 can be optimized with less impact on the optimal value of the modulation transfer function, that is, the modulation transfer function and the virtual image distance can be balanced, thereby preventing the user from experiencing visual fatigue and improving the user experience of the display device 400.

[0095] Figure 8 The present invention provides a flowchart for aligning and fixing the optical structure and display screen in a display device according to an embodiment of the present disclosure.

[0096] For example, Figure 4 and Figure 8 As shown, the best MTF value is obtained by adjusting at least one of the first parameter, the second parameter and the third parameter, the second lens structure 520 is adjusted, and at least one of the first parameter, the second parameter and the third parameter is further adjusted so that the optical structure 420 and the display screen 410 reach the best alignment position corresponding to the balanced MTF and VID, the optical structure 420 and the display screen 410 are rotated and the light power detection is performed, if the lowest position of the ghost is detected, the display screen 410 and the optical structure 420 are glued, and the MTF and VID values ​​under different field of view angles are detected, if there is a large deviation from the optimal value, at least one of the first parameter, the second parameter and the third parameter is further adjusted, and finally UV curing is performed to fix the position of the display screen and the optical structure.

[0097] Figure 8It is schematically shown that after adjusting at least one of the first parameter, the second parameter and the third parameter to achieve the optimal alignment position of the display screen 410 and the optical structure 420 in balancing MTF and VID, one of the display screen 410 and the optical structure 420 is rotated to perform optical power detection to achieve the alignment position with the lowest ghosting effect, but it is not limited to this. It is also possible to first rotate one of the display screen 410 and the optical structure 420 to perform optical power detection, and after reaching the alignment position with the lowest ghosting effect, adjust at least one of the first parameter, the second parameter and the third parameter to achieve the optimal alignment position of the display screen 410 and the optical structure 420 in balancing MTF and VID.

[0098] There are a few points to note:

[0099] (1) The drawings of the embodiments of the present disclosure only involve structures related to the embodiments of the present disclosure, and other structures can refer to general designs.

[0100] (2) In the absence of conflict, features in the same embodiment and different embodiments of the present disclosure may be combined with each other.

[0101] The foregoing description is merely an exemplary embodiment of the present disclosure and is not intended to limit the scope of protection of the present disclosure. The scope of protection of the present disclosure is determined by the appended claims.

Claims

1. An optical alignment system, comprising: A placement structure, used for placing the display device to be aligned; a semi-transmissive and semi-reflective structure, located on one side of the placement structure; Optical power meter, The placement structure and the optical power meter are located on the same side of the transflective structure, and the transflective structure is configured to reflect a portion of the light emitted by the display device to the optical power meter; The placement structure and the semi-transmissive and semi-reflective structure are arranged along a first direction, the optical power meter and the semi-transmissive and semi-reflective structure are arranged along a second direction, and the first direction intersects the second direction. The placement structure includes a first position adjustment mechanism and a second position adjustment mechanism arranged along the first direction, the first position adjustment mechanism is located between the second position adjustment mechanism and the semi-transparent and semi-reflective structure, and one of the first position adjustment mechanism and the second position adjustment mechanism is configured to rotate relative to the other around a reference line, which passes through the center of the semi-transparent and semi-reflective structure and extends along the first direction.

2. The optical alignment system according to claim 1, further comprising: The first lens structure is located between the optical power meter and the semi-transmissive and semi-reflective structure.

3. The optical alignment system according to claim 1, further comprising: at least one detector, the at least one detector comprising a first detector, the reference line passing through the first detector, The semi-transmissive and semi-reflective structure is further configured to transmit a portion of the light emitted by the display device to the first detector.

4. The optical alignment system according to claim 3, further comprising: a movable member located between the at least one detector and the transflective structure; at least one second lens structure located on the movable component; The movable component is configured to adjust the distance between the at least one second lens structure and the detector corresponding thereto.

5. The optical alignment system according to claim 1, wherein: The display device to be aligned includes a display screen and an optical structure located on the display side of the display screen, the semi-transparent and semi-reflective structure is located on the side of the optical structure away from the display screen, and at least one of the first position adjustment mechanism and the semi-transparent and semi-reflective structure is configured to move relative to the other in the first direction so that the ratio of the distance between the center of the semi-transparent and semi-reflective structure and the exit pupil plane of the optical structure to the exit pupil distance of the optical structure is not greater than 10%.

6. The optical alignment system according to any one of claims 1 to 5, wherein: The first position adjustment mechanism and the second position adjustment mechanism are further configured such that one of them moves relative to the other in at least one of the first direction and in a plane perpendicular to the first direction.

7. The optical alignment system according to any one of claims 1 to 5, wherein: The first position adjustment mechanism and the second position adjustment mechanism are further configured to rotate one of them relative to the other about a first axis parallel to the second direction and about a second axis perpendicular to the first direction and the second direction to adjust the inclination between two components of the display device respectively placed on the first position adjustment mechanism and the second position adjustment mechanism; The first axis, the second axis, and the reference line intersect at a point.

8. The optical alignment system according to claim 3 or 4, wherein: The at least one detector includes a plurality of detectors, the plurality of detectors include a plurality of second detectors, and the angle between center lines of two second detectors symmetrically distributed relative to the first detector is 120 degrees.

9. The optical alignment system according to any one of claims 1 to 5, wherein: One of the first position adjustment mechanism and the second position adjustment mechanism is configured to rotate relative to the other at an angle of ±90 degrees around a reference line.

10. The optical alignment system according to any one of claims 1 to 5, wherein: The angle between the light-splitting surface of the semi-transmissive and semi-reflective structure and the first direction is 40 to 50 degrees.

11. A method for aligning the optical alignment system according to claim 1, comprising: Placing the display device to be aligned on the placement structure, wherein the display device to be aligned includes a display screen and an optical structure located on a display side of the display screen, the transflective structure is located on a side of the optical structure away from the display screen, the first position adjustment mechanism is configured to place the optical structure, and the second position adjustment mechanism is configured to place the display screen; rotating one of the first position adjustment mechanism and the second position adjustment mechanism to rotate one of the display screen and the optical structure relative to the other; Detecting the change in optical power of the display device during the rotation process.

12. The alignment method according to claim 11, wherein: The optical alignment system further includes at least one detector, the at least one detector including a first detector, the reference line passes through the first detector, the transflective structure is further configured to transmit a portion of light emitted by the display device to the first detector, and the alignment method further includes: An image is acquired by the at least one detector to obtain a modulation transfer function.

13. The alignment method according to claim 12, wherein: The optical alignment system further includes at least one second lens structure located between the at least one detector and the semi-transmissive and semi-reflective structure. The alignment method further includes: adjusting the distance between the at least one second lens structure and the detector corresponding thereto to detect the position of the virtual image formed by the display device; adjusting at least one of a first parameter, a second parameter, and a third parameter according to the position of the virtual image to balance the modulation transfer function and the position of the virtual image, The first parameter includes the distance between the display screen and the optical structure, the second parameter includes the offset distance between the orthographic projections of the center of the display screen and the center of the optical structure on a plane perpendicular to the first direction, and the third parameter includes the angle between the display surface of the display screen and the optical axis of the lens included in the optical structure.

Images